Computer-aided systems used to measure superweak magnetic fields in a human body are created. A relaxation oscillation (RO) SQUID, magnetometer is the basis of these systems. It is shown that if the RO operation mode is utilized, it becomes possible to improve the parameters and simplify the SQUID-magnetometer electronics. The software used for preprocessing provides the digital filtration, data input and accumulation, visual signal-quality control and signal averaging and all this is done in a PC/AT. The magnetocardiogram (MCG) processing programs yield magnetic mapping, magnetic chart visualization, provide the correlational/statistical analysis and magnetic signal source localization. The biomagnetic systems are now installed in the cardiological clinic. The spesialists examine MCGs, magnetoplethismograms and perfom magnetic liver biopsy. More then 400 patients have been examined and the experience gained after such examinations shows that biomagnetic investigations aimed at human body organ disease diagnosis are of high informational value.